Switch mechanism



March 22, 1938. T. R. HARRISON SWITCH MECHANISM Original Filed Nov. 2, 1929 2 Sheets-Sheet l INVENTOR. Th w/ 11 11, BY 5, W

I ATTORNEYS.

March 22, 1938. T R. so 2,112,092

SWITCH MECHANISM Original Filed Nov. 2, 1929 2 Sheets-Sheet 2 FIG. 45.

INVENTOIg. Tiwmasiflfarrwon,

a, ATTORNEYS.

Patented Mar. 22, 1938 anaoea swrrcn mechanism Thomas R. Harrison,

Wyncote, assignor to The Brown Instrument (florrrpany Philadelphia, Fa, a corporation of Pennsylvania Divided and this application February 3, 1932, Serial No. 59,559

15 (Claims.

C ne general object of the present invention is to provide an improved switch mechanism charac terized by its'pr'ovisions for automatically opening following its adjustment into its circuit closing condition. More specifically the general object of the invention is to provide an improved switch mechanism of the type which may be designated as a self-opening switch with a time lag.

A further object of the invention is the pro= vision of a mercury or liquid flow switch will have its contacts connected by the mercury within the movable switch container when the latter is moved from one position into a second position, and in which the mercury will move by if; a retarded gravital action to separate said contacts whenever the container is left stationary for a predetermined time interval in either of said positions or in any intermediate position.

A further object of the present invention is the provision of a switch mechanism for use in and as a part of automatic control apparatus and adapted to serve the ordinary control switch purposes of such apparatus, automatically opening the controlled circuit when the operation of the control apparatus requires such circuit opening action, and also to serve as a safety device opening said controlled circuit whenever the control apparatus becomes inoperative from any cause. In particular my improved switch mechanism is adapted for use in automatic temperature control systems in which a control instrument perlodically effects a control action in response to the action of a thermo-electric device or pyrometer exposed to the heat of the device controlled. In such case, when the temperature controlled is that of an electrically heated or fuel fired furnace, the control action may be made on the fuel supply provisions thereof as disclosed, for example, in the patent to Richard P. Brown, No. 1,489,920, granted April 8, 1924. In such use of my improved switch mechanism, the latter is not only actuated by the thermo-electric device or pyrometer to prevent an undue increase in furnace temperature normal operation, but also operates to prevent the furnace temperature from rising unduly when an abnormal operating conditlon occurs, such, for example, as when any of the control instrument parts or the thermo-electrlc circuit become inoperative. I 50 The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of t invention, however, its advantages and spdclfic objects attained with it ref- (Cl. wit-33) er nce should be had to the accompanying draw ings and descriptive matter in which I have illus= trated and described preferred embodiments of the invention.

Of the drawings:

Fig. l is a perspective view representing some= what diagrammatically a portion of a control system incorporating one embodiment of my inven== tion;

Fig. 2 represents in perspective an alternative form 0;" switch mechanism;

Figs. 8, d and 5 are views similar to Fig. 2 of other forms of switch mechanism;

Fig. 6 is a view similar to Fig. 1 illustrating a modified form of control apparatus;

Fig. 61%. illustrates the safety table of 6 in the starting position;

Fig 7 illustrates the switch of Fig. 6 in a different position; and

Fig. 8 represents a modified form of switch.

in the drawings and particularly in Fig. 1, I have illustrated a portion of an automatic temperature control system in which the control instrument comprises a galvanometer coil element A carrying a pointer A swinging about the suspension axis of said element in accordance with the variations in value of the E. M. F. generated by a pyrorneter A exposed to the heat of a furnace (not shown) and connected to binding posts on the instrument by leads 4 and 2. A indicates the instrument scale immediately below which the free end of the pointer swings.

The furnace temperature is regulated by the control instrument periodically effecting a control action on the fuel supply means of the furnace. The mechanism normally effecting this action comprises a shaft B' slowly rotated in a clockwise direction by a time controlled electric motor B, such as a synchronous motor, and on which shaft an operating cam C is rigidly mounted. cam C is formed with arcuate surface portions C and C and a pair of diametrically opposite notched surface portions C and C. A cam follower D, having its upper end secured to a horizontal shaft A is positioned at one side of and adjacent to the cam C. The lower end of the follower is formed with a laterally projecting end D, which by the weight of the follower is maintained in contact with the adjacent cam surface.

With the foregoing arrangement the shaft A receives a pair of oscillations during each revolution of the cam. This shaft is arranged at the rear of the scale A and carries a control table E positioned below the scale at a point corresponding to a desirable operating temperature.

The table consists of a U-shaped member having 'its legs E angularly fixed on, but slideable longitudinally of, the shaft A as, for example, by providing the shaft. A with a key rib A passing through notches in the legs E. The base portion of the table has a straight contact edge E and a vertical finger E for limiting movement of the pointer.

As shown in Fig. 1, while the follower end contacts with either of the arcuate cam surfaces the table is spaced a predetermined distance below the lower'edge of the scale, and as the follower end D moves inwardly in either cam notch, the table is moved in a clockwise direction until obstructed by the lower edge of the scale or by the pointer A when the latter indicates a temperature value corresponding to the portion of the scale towards which the table is moving. The pointer would then limit the inward movement of the follower.

At the side of the cam C opposite the follower D is located a pendulum G secured to a rotatable shaft G and having an adjustable weight G at its lower end. The upper end G of, the pendulum carries a laterally projecting stud G which is adapted to be engaged by the end of a bell crank lever F pivoted at F when the pendulum is tilted from its free position. The lever is held in the locking position shown in Fig. l by a tension spring F. The vertical portion of the lever has a lateral extensionl arranged adjacent a projecting contact edge D formed on an intermediate portion of the follower D. The lever extension is arranged to be actuated thereby only when the follower is permitted to move inwardly to the full extent of the cam notch. The pendulum has a laterally inclined arm G at the upper end of which a follower pin G is mounted and arranged to contact with the periphery of the cam C at a point substantially diametrically opposite the contact point of. the follower D. Therefore, when the follower D begins its inward movement into the notch C the pin G is about in a position permitting pendulum movement into the notch C.

When the pointer A is below the control table as shown in Fig. 1, the follower D can move inwardly to the full extent of the notch C During the latter portion of this movement the intermediate contact edge D engages the lever F to move the latter out of engagement with the pendulum' stud G The pin G being then in a position to permit clockwise movement of the pendulum, the latter on its release immediately swings outwardly causing the shaft G to be partly rotated. A tilting lever G mounted on the shaft G by an arm G is simultaneously raised to actuate a combined control and safety switch as hereinafter described.

The fuel supply means of. the furnace is preferably controlled through an operating circuit comprising conductors 3 and 4, the making and breaking of the circuit being effected by the above mentioned switch. In the construction shown in Fig. 1 the switch is of the liquid flow or mercury type having a container part in the form of an elongated sealed glass envelope or tube H with a pair of depending chambers or leg portions H and 1-! at one end. The terminals or electrode ends H and H of the conductors 3 and l are mounted in the chambers H and H, respectively, the terminals being sealed in the glass and extending to a point below the top of the corresponding chamber. The tube contains a predetermined amount of conducting liquid. such as mercury, which when in the terminal end of the tube is sufficient to overflow the chambers H and H and thus establish an electrical connection between the operating circuit terminals. The tube is mounted on a hinge or rock shaft H, which is shown as extending between the tube chambers.

In the switch illustrated in Fig. 1, the flow of mercury towards the free end of the tube is restricted by a transverse baille H which is in fluidtight contact with the walls of the tube and has its lower portion provided with an orifice H through which the mercury flows away from the terminal end of the tube as long as the mercury level therein is higher than the orifice.

The tube is also constructed to permit a substantially unobstructed flow of mercury towards the terminal end of the tube when the lever G" is actuated. For this purpose the bafiie H is vertically inclined towards the terminal end of the tube and its upper section cut away as indicated at H". The mercury then flows over the upper edge of the baffle in an amount dependent on the rapidity of the tilting movement and the angle to which the tube is tilted.

With the parts constructed and arranged as described, the tube H will be tilted by the lever G every time the pendulum is released from its locked position. The pendulum can only be released when the position of the pointer A indicates a temperature below the desirable value. With such pointer position and with the cam C rotating in a clockwise direction, the follower D will move inwardly into the notch C to its full extent, thereby actuating the bell crank lever F to release the pendulum G and tilt the switch tube H. The mercury in the free end of the tube H then flows over the baiile H into the terminal end of. the tube to overflow the chambers H and H and close the operating circuit. The lever G drops out of contact with the tube on the return movement of the pendulum at the end of which movement the pendulum is again locked in position by the cam. The tube thereafter returns to its normal position as a result of the relatively slow flow of mercury through the orifice H, as indicated in Fig. 1. After that flow has continued for a predetermined interval, the mercury no longer connects the switch contacts H .and H and the operating circuit is broken.

The normal position of the tube is determined by the position of an adjusting screw H" mounted in a support H" and arranged to obstruct a lateral portion H of a tube extension member H This screw can therefore be adjusted to regulate the length of the contact making period. The rate of flow of the mercury towards the free end of the tube is desirably regulated to effect a contact making period about 50% greater than the interval between successive oscillations of the follower. For example, the interval between oscillations may be 15 seconds and the contact making interval approximately 22 seconds. The cam C being continuously rotated, a similar control action is eifected when the notch C4 reaches the follower D. If the pointer A is still below the position corresponding to the desirable operating temperature, the switch tube H is again tilted and the operating circuit remains closed. When the pointer A assumes a position indicating that the furnace has reached the desirable operating temperature, the subsequent upward movement of the control table E will be obstructed by the pointer A and the movement of the follower D into the octaiiaoca responding cam-notch C or C will be insufli cient to actuate the bell crank lever F. The pendulum G and switch tube H will then remain in the position shown in Fig. 1 and the circuit will be broken approximately 7 seconds after this such ineffective control action. The switch thus operates to make the circuit under the ac= tion of an external force, maintains the circuit for a predetermined period after the external force is inefiective, and is self-opening at the end of that period.

In the event of one or more of the operating parts such as the motor B, becoming inoperative, it is extremely desirable to cut oil the fuel supply means to prevent overheating of the furnace or injury to the fluid or material beingtreated. If the motor B becomes inoperative while the parts are in the position indicated in Fig. 1, then as will be apparent no movement of the follower D can occur and, since the pen dulum remains locked, the switch H will re main in the position indicated. The operating circuit if then closed will open at the end of the contact following the last previous oscillation of the member G.

On a break in the actuating circuit of the in= strument due to any cause, such as a break in the pyrometer elements or leads, the pointer A will immediately swing to the zero scale position. Thereafter, the control mechanism insofar as it has been previously described herein would opcrate periodically to continuously maintain the operating circuit, since the pointer A would be out of the path of movement of the control table E. Such operation would permit the furnace temperature to rise far above the desired value. To prevent the occurrence of this undesirable condition on the failure of the instrument circult, I have provided additional mechanism for automatically effecting a control action which breaks the operating circuit. This mechanism comprises a safety table I mounted on the shaft A in the same manner as the control table The safety table I is also formed by a U-shaped mem her having supporting arms I, a pointer limiting finger I and a horizontal contact edge 1 The tables E and I are preferably mounted on the shaft with their contact edges E and I at the same level. The safety table I is arranged adjacent the zero scale marking. When the pointer swings to a position between the safety table 1' and scale, movement of the follower D will be limited to an amount insuflicient to actuaw the lever F. The operating circuit will thus be au tomatically broken at the end of the circuit contact making period.

Since the pointer A is normally adjacent the zero marking on the scale when the furnace is cold, it is necessary to eliminate the normal control effect of the safety table I to heat the furnace. To that end, I have provided mechanism for closing the operating or control circuit at starting. Such mechanism as illustrated in Fig. 1 consists of a lever D6 secured on a rotat able shaft D and arranged to engage the outer end of a bar D which is pivoted at D on the cam follower D. The bar D is normally held in the full line position shown in Fig. '1 by the action of gravity, further lower movement being" prevented by a stop D on the follower D. At starting the lever D is rotated into contact with the bar D to shift the latter to the dotted'line position shown in Fig. 1, in which position the bar extends beyond the contact edge D When the next periodic actuation of the follower D occurs notwithstanding its limited amount due to the engagement of the pointer A by the safety table I, the bar D will engage and move the bell crank lever F sufficiently to effect the release of the pendulum and the consequent closing of the operating circuit.

As the furnace temperature thereafter rises the pointer A. will pass beyond the range of ac tion of the safety table I and the follower D can then swing inwardly lower movement carries the arm D end of the starting arm D and the arm D re= turns to its normal position. The control ap paratus performs its usual control operations to beyond the maintain the operating circuit closed until either i the desirable temperature is reached or the oper ating parts or instrument circuit rendered. lnef= iective. will be noted that the pendulum ar rangement insures a positive tilting movement of the switch, regardless of what may efiect the other operating parts after its release.

In 6 l" have illustrated a modified form of control apparatus in which the operating parts have the same general construction and mode of operation as those illustrated in Fig. i, but differ therefrom in the specific construction and ehfec= tiveness of the safety provisions'and by the automatic operation of the furnace starting provisions. In this construction the control table Eis identical in construction and mode of operation with the control table E of Fig. 1. The motor B rotates a cam K which, as shown, is provided with four projecting arms Ii, each of which is formed with a straight edge portion K and a curved edge portion K A cured on the shaft A is provided with a projecting lower portion L having its upper edge formed by high and low steps L and L, respectively. A pin L projects laterally therefrom to engage the adjacent cam surface and is held in contact therewith by a counter-weight A on a shaft rod A The switch comprises a lever li/i, at M to a suitable support. The opposite end of the lever is mounted in a slot M at one end of a second lever M extending transversely thereto and having its opposite end pivoted at hi it stud M projects laterally from the lever ii i into contact with one of the cam surfaces. The tube ii in this construction, as shown in Figs. 6 and 7, contains a longitudinally extending bafile or scoop N of insulating material and formed with an inclined section N leading to a reservoir N into which the terminal H extends.

second reservoir N of lesser capacity is provided for the terminal H and the portion or" the scoop between the reservoirs made suihciently low to permit the mercury to bridge the terminals and close the circuit while only a portion of the mercury in the tube is in the reservoir section. The reservoir N is connected by a drain opening N with the portion of the tube below the scoop and through w ch opening the mercury flows while the reservoir liquid level is higher than that in the bottom of the tube. The opposite end of the scoop is spaced from the corresponding tube end to provide a liquid passage N With the foregoing parts arranged as described, the control cycle which in normal operation periodically occurs consists in raising the tube H to the position shown in Fig. 6 under the action of one of the cam surfaces K in which position substantially all the mercury in the tube collects mechanism in this construction mercury switch tube H fixed on a to its full extent. The folcam follower L, se-

one end of which is pivotally connected 4 in the lower end. While the stud M is being raised, the follower pin L moves inwardly on the corresponding cam surface K to an extent dependent on whether or not the pointer A is in a position to obstruct the edge of the control table E. If the table is not obstructed, the follower L moves inwardly on the cam to a point at which the stud M will slide down into contact with the low step L of the follower after the stud has passed over the upper end of the cam surface K".

This operation causes the switch tube to be moved to the position indicated in Fig. '7. The tilting movement causes the mercury in the lower end of the scoop to flow over the surface N into the terminal reservoirs N and N, the mercury level therein then being sufficient to'close the circuit between. the operating terminals. The mercury in the reservoirs drains through the opening N while the tube is returned by the cam to the position shown in Fig. 6. The pointer contlnuing in a position below the control table, the foregoing cycle of operations will be periodically repeated, the duration of the cycle being less than the time required for enough of the mercury to drain or leak through the opening N to break the operating circuit.

If, however, the pointer A is in a position to obstruct the control table, the follower L is prevented from moving to its full extent. In that case the follower high step L is in a position to receive and prevent the stud M from dropping sufficiently from its raised position to tilt the tube and replenish the mercury in the reservoirs. The continued draining of the mercury from the reservoir N' then breaks off the operating circuit. If the switch actuating mechanism becomes ineffective while the switch is in any of its normal operating positions, the operating circuit will be automatically opened by the self-draining construction of the switch. This self-opening operation of the switch is effective even in the extreme position of the switch shown in Fig. '7.

In the form shown in Figs. 6 and 6A, the mechanism for automatically preventing actuation of the switch tube when the galvanometer circuit is broken comprises a safety table P consisting of a plate member P pivotally connected at P on the outer end of a U-shaped supporting member P which is rigidly connected to the shaft A in the same manner as the table E. The plate member P has a normally vertical section terminating in a pointer limiting finger P projecting above a horizontal contact edge P which is preferably at the same level as the contact edge E of the control table. The plate P also has a horizontal section which terminates in a straight edge IE and a finger P' perpendicular thereto. As shown in Fig. 6, the plate is normally in a position in which the center of gravity indicated at g is at the righthand side of the pivot point P further angular movement of the plate in that direction being prevented by a stop P on the horizontal section engaging the member P When so arranged, the pointer will be engaged by the finger P and by contact edge P as the member 1? is periodically raised. Since the edge P is at the same level as the control table, a corresponding control action will be effected to limit the movement of the follower and thus prevent the actuation of the switch. The distribution of the weight of the plate member prevents any angular movement when the pointer obstructs the edge P.

is to be started into operation, it is necessary to render the safety table ineffective to prevent the closing of the operating circuit. The plate P is therefore turned to the position indicated in Fig. 6A, in which position a stop P on the vertical section engages the supporting member P, the center of gravity moving to the position indicated. In this position the pointer A will have no obstructing action and a corresponding contact making control action is performed. The furnace temperature increasing, the pointer will move towards the high temperature scale end, and in the course of that movement will engage the finger P" and contact edge P to reset the plate in its normal position. The furnace temperature increasing, the pointer moves out of the operating range of the safety table and the switch actuating and non-actuating control actions heretofore described may take place as conditions require. The safety table construction described is advantageous in that the operating circuit will be maintained closed during starting without attention from the operator and because the table is automatically returned to its normal position when the furnace temperature rises.

In Figs. 2, 3, 4 and 5 I have illustrated other forms of self-opening switch mechanisms adapted for use as combined control and safety switches. In Fig. 2, for example, a flow type tube switch is standard form and does not incorporate the time lag provisions, but with which a time lag action is secured by mounting an auxiliary mercury tube Q on the same shaft Q and providing the auxiliary tube with a baffle Q similar in form to that of Fig. 1. In this construction the pair of tubes are simultaneously tilted by the tilting lever (3: and the restricted flow of the mercury through the baffle orifice Q in the tube Q is sufficient to delay the return of the tubes to their normal position and thereby retard the flow of mercury in the tube Q away from the terminals H and H sufficiently to maintain the operating circuit closed for a predetermined period.

In Fig. 3 a similar action is effected by pivotally mounting a mercury switch tube QA on a shaft R carrying a ratchet R. The tube has an extension R carrying a pawl R pivotally connected thereto and arranged to engage successive ratchet teeth as the tube is tilting about its pivot by the lever G". If, for example, the pawl is advanced one tooth before the lever G" drops, the ratchet will be rotated as indicated by the weight of the tube and cause a fan R to turn. The air resistance to the fan blades impedes the movement of the ratchet and consequently delays the return of the tube to its normal position.

The switch mechanism of Fig. 4 operates on substantially the same principle as that of Fig. 3, the tilting of the mercury switch tube QB of Fig. 4 advancing a pawl S on a ratchet S. The resultant rotation of the ratchet and the shaft S is retarded by the movement of a liquid or granular material through orifices S in the diaphragms S, which divide an annular chamber mounted on the ratchet shaft into a plurality of arcuate sections S In Fig. 5 the mercury switch tube QC on being tilted about its pivot axis R moves the extension R to depress the piston T in a dash pot T. The subsequent upward movement of the piston will be impeded by the pressure of the atmosphere on the piston, the one-way valve '1' opening to When the furnace shown in which the tube Q is of a' .aiiaoea permit free down movement and closing to retard up movement of the piston.

In Fig. 8 a modified form of switch tube is shown incorporating the general construction of the tube of Figs. 6 and 7, except that the scoop V is formed with a single leaky reservoir V, and the terminal H carries a cup V of arc resisting material such as fused quartz or porcelain at its lower end, whereby the break in the terminal circuit will advantageously occur at the upper edge of the porcelain cup rather than on a glass edge such as is intermediate the reservoirs of Fig. "i. A drain hole V is also provided in the tube of Fig. 8 and the latter may be actuated in the same manner as the tube of Figs. 6 and 7 to effect the various control actions. it will he understood that the switch tube in this and the other constructions can be advantageously filled with a spark quenching and heat conducting me such ashydrogen.

The control apparatus disclosed herein, em Foodies various novel features of construction and arrangement invented by me, but not claimed herein as they are fully disclosed and claimed in hawnt raise-2o, granted July ith, 1933, on my prior application, Serial No. @4280, filed November 2, 1929 of which the present applica-= tion is a division.

While in accordance with the provisions or the statutes, l have illustrated and described the best forms of ernhodirnent of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form and arrangement of the apparatus dis closed without departing from the spirit of my invention as set forth in the appended claims and that in some cases certain features oirny invention may be used to advantage without a corresponding use of other features.

Having now described my invention, what 1; claim as new and desire to secure by Letters Patent, is:

l. A switch mechanism comprising a container, a support in which said container is mounted for movement through a limited range, mercury within and paijially filling said container, per vious partition means within said container di viding the latter into a compartment and a stor= age space lower than said compartment in all operative positions of said container and pro viding for flow loetween said compartment and space, conducting terminals extending into said compartment, said partition means being adapt ed to permit the quick displacement of mercury from said space into said compartment to thereby connect said terminals when said container is subjected to an actuating impulse giving said container a predetermined movement in one di rection within said range, and to permit the slow movementof mercury out of said compartment to thereby interrupt the connection between said conductors solely as the result of gravitational action occurring during a predetermined time in-= terval following each such actuating impulse.

2. In a switch, the combination with a container adjustable through a limited range, pervious partition means within said container dividing the interior of the latter into a compartment and a drainage space lower than said compartment in all operative positions of said container with flow passages between said compartment and drainage space adapted to permit mercury received in said compartment to slowly drain from latter in any position of the container, and to permit the rapid movement of mercury into said compartment from said space when said container is given an adjustment within said range, mercury partially filling said container, and contacts extending into said compartment and connected by mercury therein.

3. A mercury switch comprising a container movable between two positions, mercury partially filling said container, pervious partition means within said container providing a leaky reservoir space above a drainage space portion of -e container in any operative position oi'the Latter and quiclg y filling with mercury when said con tainer is moved from. one of said positions into the other, and from which mercury escapes ly into said drainage space portion in any posl tion of the container, and switch contacts tending nto said reservoir space and connected by mercury therein.

4. A switch mechanism comprising in corn" tion a movable mercury switch container, he one partition means within container providing a leaky reservoir within said container a drainage space lower than said reservoir in any operative position of said container, mercury witln'n said container moved into said reservoir from said drainage space by a switch closin 1: movement of the container, and switch contact extending into the container and connected h; mercrny within said reservoir, the rate of leakage out of said reservoir into said drainage space being such as to break connection between said contacts when said con nor is left stationary for a predetermined t e interval following a switch closing movement.

5. A mercury switch comprising a tubular con-- tainer movable about a sulz-stantially hou'cntal aids, mercury partially filling said cont iner, scoop member arranged longitudinally in said container and having an inclined section an a reservoir ection alcove a drainage space peril of the container, a oi circuit teimina c positioned in said reservoir section and electri cally connected by mercury therein when said section is filled with mercury to a predetei level, said scoop member being arranged to; mercury over said clined section into said reser voir section on a lting movement of said container, and said reservoir having a drain opening in its lco-ttorn.

6. A mercury switch comprising a closed tuhu lar container movable about substantially lie-ri Zontal axis, mercu'y partially filling said con tainer, a scoop member arranged longitudinally in said container having an inclined section above a drainage space portion oi said conta ner and a leaky mercury reservoir section, p circuit terminals positioned in said resez on section and electrically connected, by merciuy therein when said section is filled with mercury to a predetermined level, and a cup member or are resistant material carried by one of said terminals, said scoop member being arranged topass mercury over said inclined section into said reservoir section on a tilting movement of said container.

7. A mercury switch comprising a container mounted for movement between two positions, mercury partially filling said container, perviouspartition means in the latter providing a leaky reservoir space above a drainage space portion of the container and quickly filling with mercury when said container is movedinto one of said positions from the other and from which the mercury thereafter slowly leaks into said drainage space portion. the center of gravity of said container shifting as a result of the mercury movement to maintain the container in said one position until a predetermined leakage from said space has occurred and then moving the container into its other position, and switch contacts extending into said reservoir space and connected by mercury therein.

8. A mercury switch comprising a container mounted for movement between two positions, mercury partially filling said container, pervious partition means in the latter providing a leaky reservoir space above a drainage space portion of the container and quickly filling with mercury when said container is moved from one of said positions into the other and from which the mercury thereafter slowly leaks into said drainage space portion, a cup-shaped receptacle mounted in said container in position to be submerged by the mercury in said reservoir space when the latter is filled but not after mercury has leaked out of said space, a switch terminal in contact with mercury in said receptacle, and a second cooperating switch contact extending into said reservoir space.

9. A mercury switch comprising a closed container, a body of mercury partially filling said container, means for giving the container guided switch closing movements, pervious partition means within said container providing a contact compartment and a drainage space lower than the latter in every operative position of said container and with a relatively free inlet from said space to said compartment through which the latter quickly fills with mercury on each of said switch closing movements and providing a relatively restricted outlet to said space from said compartment through which the latter empties slowly following each of said movements and contacts extending into said compartment and connected by mercury therein, whereby the mercury connection between said contacts may be continuously maintained by said movements when repeated with such frequency that the time interval between any two successive movements does not exceed a predetermined maximum period and whereby the connection between said contacts is interrupted whenever one of said movements is not followed by a subsequent movement within said maximum period.

10. In a switch mechanism, the combination of a support, a container adiustably mounted in.

said support, mercury partially filling said container, pervious partition means within said container providing a compartment and a space lower than the latter in every operative position of said container and into which mercury is slowly transferred from said compartment by an inherent gravitational action following each adjustment of the container transferring mercury to said compartment from said space, and from which mercury may be transferred rapidly into said compartment by a single adjustment in one direction of said container relative to said sup port, means for impressing an external force on said container to effect such adjustment and contacts extending into said compartment and connected by the mercury transferred into said compartment by each such adjustment.

11. A mercury switch comprising a closed container mounted for movement between two positions, a body of mercury partially filling said container, pervious partition means in said container interposed between the lower parts of displaced portions of the latter, contacts extending into one of said portions, said container being disposed and adapted for movement under the action of an applied force into one of said positions and to thereby quickly move mercury into the last mentioned portion over said partition means from the other of said displaced portions, and being disposed and adapted to permit a slow gravitational fiow of mercury through said partition means, following each such action of an applied force, into said other portion from the container portion into which the contacts extend.

12. A switch mechanism comprising a container adjustable between two positions, mercury partially filling said container and adapted to be displaced into or'from a localized portion thereof accordingly as said container is moved into one or the other of said two positions, contacts extending into the said localized portion and adapted to be connected by mercury therein, said container being adapted to be moved into said one position by an applied force, and having a slow acting bias to move from said one position into said other position.

13. A mercury switch mechanism comprising a pivoted container, pervious partition means therein separating a contact receiving portion and a drainage portion of the container, contacts extending into said contact receiving portion, mercury partially filling said container, the latter being adapted to be tilted by an applied force to thereby displace mercury over said partition means from said drainage portion into said contact receiving portion and to thereby bias said mechanism for a slow gravitational flow of mercury from said contact receiving portion into said drainage portion whereby the mercury so displaced whenever said container is tilted by an applied force, establishes a conducting bridge connection between said contacts, and said bridge so established is automatically broken by the said slow flow of mercury at the end of a predetermined time interval following each force application to tilt the container without repetition of such application in the meantime.

14. A mercury switch mechanism comprising pivoted container means adapted for movement between two positions, a body of mercury contained in said container means, pervious partition means provided in said container means, interposed between lower parts of displaced portions of the latter, contacts extending into a portion of said container means, said container being disposed and adapted for movement under the action of an applied force into one of said positions and to thereby quickly move mercury into the last mentioned portion to bridge and close said contacts and being disposed and adapted to permit a slow flow of fluid through said partition means, following each such action of an applied force from one to the other of said displaced portions whereby said contacts are unbridged and opened by said mercury after a predetermined time interval.

15. A switch element adapted to be operated between a switch opening position and a switch closing position and adapted to form a part of mechanism including continuously operating means adapted to operate said switch element in a cyclic manner between its switch opening and closing positions, means operating independently of said operating means and active in all positions of the latter for biasing said element from said closed position, and means retarding said biasing means,

THOMAS R. HARRISON.

CERTIFICATE OF CORRECTION,

Patent'No. 2,112,092o March 22, 1958.

THOMAS R, HARRISON.

It is hereb; certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line 25, claim after "moved? insert the word rapidly; line 55,

claim 6, strike out the words "above a drainage space portion of said container" and insert the same after "section", line 56, same claim; and that the said Letters Patent shouldbe readwith these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of June A. Dm 1958.

. Henry Van Arsdale,

(Seal) v Acting Commissioner of Patents CERTIFICATE OF CORRECTION.

Patent'No. 2,112,092. March 22, 1958.,

THOMAS R. HARRISON.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, second column, line 25, claim L after "moved'fi insert the word rapidly; line 55,

claim 6, strike out the words "above a drainage space portion of said container" and insert the same after "section", line 56, same claim; and that the said Letters Patent shouldbe r'eadwith these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of June, A. D. 1958.

. Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

